Automatic switching apparatus



Nov. 22, 1938. J. E. OSTLINE AUTOMATIC SWITCHING APPARATUS Filed June11, 1937 INVENTOR.

JOHN E.OSTLINE ATTORNEYS Patented Nov. 22, 1938 PATENT OFFICE 2,137,507AUTOMATIC SWITCHING APPARATUS John E. Ostiine, Chicago, Ill., assignorto Associated Electric Laboratories, Inc., Chicago, 111., a corporationof Delaware Application June 11, 1937, Serial No. 147,617

, 14 Claims.. (01. 179-215) The present invention relates to automaticswitching apparatus and more particularly to automatic switches of thetype adapted for use in signalling systems.

Various forms of the so -caled drum type of circuit controller are knownin the electrical arts. These controllers almost universally comprise arotatable drum or cylinder having mounted thereon conducting orcommutating segments, and wipers or brushes associated with therespective commutating segments and adapted to engage the same atpredetermined points in the rotation of the cylinder about its axis ofrotation. In each instance the manner in which the oommutating segmentsand the associated brushes are arranged is dependent upon the particularuse to be made of the controller. The means provided for rotating thecylinder and the control means therefor also depends upon the use to bemade of a particular type of controller. In general, this type ofcircuit controller has not been extensively used in the signalling arts,for the reason that it is comparatively bulky in construction and isuneconomical in first cost as compared to other forms of rotaryswitches.

It is an object of the present invention, therefore, to provide animproved automatic switch of the form noted, more particularly suitedfor use in the control of signalling circuits, which is of simple,economical and compact construction, and which is capable of selectivelyconnecting a line incoming thereto, to any one line of two groups oflines outgoing therefrom by twice utilizing the commutating segments ofthe switch.

In general, the object as set forth above is realized in accordance withthe present invention by providing a switch of the form noted, whereinthe commutating segments mounted on the cylinder are spirally arrangedwithin a segment of the circumferential surface of the cylinder, and thewipers associated with these segments are arranged in two groups, thewipers of each group being disposed to engage the cylinder along adifferent line, and the two lines thus formed defining a segment of thesurface of the cylinder slightly greater than that within which theconducting segments are confined. By this arrangement, and during aportion of a revolution of the cylinder, the wipers of one group aresuccessively engaged by their respective associated segments, and duringanother portion of the revolution the wipers of the other group aresuccessively engaged by their respective associated segments. In thismanner, the

conducting segments are twice utilized for selectingany line included ineither of two groups of lines respectively terminating at the two groupsof wipers. Further improvements in the switch structure are describedspecifically hereinafter which pertain to the particular arrangement ofthe elements whereby the above operating features are obtained.

The novel features believed to be characteristic of the invention areset forth with particul0 larity in the appended claims. The inventionitself, however, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the specification taken in connection withthe accompanying drawing in which Figure 1 illustrates an automatictelephone system having embodied therein a switch constructed andarranged in accordance with the present invention; Fig. 2. is a viewpartially in section illustrating the details of certain of the elementsof the switch shown in Fig. 1; Figs. 3 and 4 are end and side views,respectively of the switch shown in Fig. 1, and Fig. 5 is a sectionalview taken along the lines 5-5 of Fig. 4. Referring now moreparticularly 'to Fig. 1 of the drawing, there is illustrated inpartially diagrammatic form an automatic-telephone system havingincorporated therein automatic switches constructed and arranged inaccordance with the present invention connected tofunction as lineswitches, and numerical switches, preferably of the well-knownstep-by-step type, for accomplishing the selection of called lines. Ingeneral, the system comprises a plurality of subscribers substations,two of which are shown at A and B, adapted to be interconnected by meansincluding their respective associated subscribers lines I00, lill, etc.,and switch trains includin the aforementioned line switches, andintermediate and final impulse responsive selector switches. Theseswitch trains, when established, may individually comprise a'line switchof the form noted associated with the calling subscriber's I24, etc.Each of the latter switches, in turn; has access to .final selector orconnector switches arranged in groups, each switch of each group havingits bank contacts connected to subscribers lines and multipled to thecorresponding bank contacts of each of the remaining switches in thesame group.

Thus, the selector switch I20, has access over trunk lines to connectorswitches, one of which is indicated generally at I30, in the bankcontacts of which the subscribers line IOI terminates. It is well knownthat by this general arrangement, any subscriber may by a propermanipulation of the impulsing device conventionally projected at hissubstation, establish a talking connection between his line and anyother idle subscribers line in the system.

Each of the final and intermediate impulse responsive selector switchesincluded in the system, may be of any desired form, although preferablyis of the well-known Strowger type, comprising bank contacts arranged inlevels, each level corresponding to a particular group of succeedingswitches or subscribers lines, wipers for engaging the bank contacts,ratchet and pawl mechanisms for imparting translatory and rotarymovements to the wipers, vertical and rotary magnets cooperating withthe respective ratchet and pawl mechanisms, a release magnet and controlmeans whereby the respective selecting functions of the switch arecarried out in response to the transmissionv of impulses thereto. Thearrangement of the control means for the switches is difierent,depending upon whether a particular switch is used in any intermediateor final selecting capacity. In switches adapted to perform theintermediate selecting functions, the control means for each switch isarranged so that the switch is responsive to a single series of impulsestransmitted thereto to select a particular level of bank contactscorresponding to a particular group of succeeding numerical switches,following which the switch wipers are automatically rotated until anidle switch in the selected group is found. The control means embodiedin those of the selector switches which are used in a final selectingcapacity are arranged to be responsive to two series of impulsestransmitted thereto, to select not only the cup of desired subscriberslines, but also the particular called line in the selected group oflines.

Neglecting for the present, the details of the line switch H and thecontrol means associated therewith, the system as described above isentirely conventional in form, and its operation is well understood inthe art. In brief, when a subscriber, such for example, as thesubscriber at the telephone A, initiates a call over the line I00 to'asecond subscriber's telephone, such for example, as the telephone B, bylifting his receiver from its hook, the line switch I I0 associated withthe calling subscribers line operates to select an idleintermediate-selector switch, and to condition the same to be responsiveto impulses transmitted from the impulse device at the telephone A. As-

noted above, each of the selector switches has access to one or moreconnector switches at which any subscribers line of the systemterminates. Thus, if the selector switch I20 for example, is seized bythe line switch IIO, it operates in response to the dialing of the firstdigit at the substation A, to translate its wipers vertically to acontact level correspondingto the group or connector switches at whichthe called line IOI terminates, following which it automatically rotatesits wipers into engagement with a set of contacts corresponding to thefirst idle connector switch in this group, such for example, as theconnector switch I30. Thereafter, and in response to the dialing of thesecond digit, the connector switch, through the operation of itsvertical magnet and the associated ratchet and pawl mechanism,translates its wipers vertically to a position opposite the level ofbank contacts in which the conductors of the line called llilterminates. With the switch train in this condition, and when the finalor third digit is dialed, the rotary magnet of the connector switch incooperation with its associated ratchet and pawl mechanism, operates torotate the switch wipers into engagement with the particular bankcontacts at which the conductors of the called line IIlI terminate.

The system conventionally includes means whereby the called line, uponbeing seized, is tested to determine its idle or busy condition, ringingcurrent and ring-back tone current are automatically transmitted to thesubstations of the called and calling parties in case the called line isidle, and busy tone current is transmitted to the receiver at thecalling substation in case the called line is found busy. The release ofthe connection as established in the above-described manner, may beeither under the control of the calling party or the last party to hangup, as desired.

Turning now to the construction and arrangement of the line switch III),forming more particularly the subject matter of the present invention,and considering Figs. 1, 2, 3, 4 and 5 together, the switch there showncomprises a hollow cylinder I0, arranged for rotation about itslongitudinal axis on a rotatable shaft II carried by a frame I2, andhaving mounted thereon conducting segments I3, I4 and I5, which areadapted to be engaged by wipers IS, IT and I8, mounted on an insulatingmember l9 also supported on the frame I2. The wipers may be mounted onthe member IS in any suitable manner, but preferably are embeddedtherein during moulding of this member. Means indicated generally at 20and comprising a stepping magnet 2| and a ratchet and pawl mechanism areprovided for imparting step-by-step rotary movement to the cylinder I0.

Preferably the cylinder III is constructed of insulating material, suchfor example, as Bakelite or hard rubber, and is mounted on the shaft IIby means comprising the two end caps 22 and 23. As best shown in Fig. 2,the shaft II is provided at its left end with a squared portion 24, uponwhich the ratchet wheel 25 of the ratchet and pawl mechanism is mounted,and with a flared portion 26 for engaging the end cap 22 when theelements of the drum are assembled. A clamping nut 21 threaded onto theright end of the shaft II, as shown, serves to clamp the caps 22 and 23against the ends of the cylinder I I! to provide a rigid assembly.Similarly a nut 28, screwed onto a threaded portion of the left end ofthe shaft I I serves to clamp the ratchet wheel 25 in position. The twoextremities of the shaft and an intermediate portion 28' thereof engagebearing surfaces formedby the inner surfaces of drilled openings in sidemembers 29, 30, and 3" 0f the frame l2. Cut clrcumferentially around theouter surface of the cylinder III, are guide grooves II, 32, 23, etc.,having bottoms of V-shaped cross section and within which the conductingsegments II, I4 and ll are mounted. For the purpose of mounting. thesegments, each thereof is provided with a threaded shank which extendsthrough an opening of slightly greater diameter drilled through thebottom of the guide groove in which it is mounted, and upon which a nutis screwed. Preferably, the head of each conducting segment is providedwith a V-shaped groove, and is countersunk in the bottom of its guidegroove, so that the V-shaped outer surface thereof forms a continuationof the V-shaped bottom surface of the groove. In this manner, theengaging return bent portion of each. wiper is easily slidable along thebottom surface of its associated groove into engagement with theconducting segment therein, and when engaged with a segment a two-pointcontact is provided between the segment and the wiper. v

' Referring now more particularly to Figs. 3 and 4, it will be seen thatthe magnet2l included in the motor means 20, is mounted on an extension34 of the frame side members 30' and 29 by means comprising a screw 35.A combination heel and side piece 36 is also mounted on the extension34, and supports a spring assembly 31 comprising a pair of'contactsprings for. co n trolling the energization of the magnet 2|. Thesesprings are insulated from each other and from the frame I2 in themanner illustrated. The ratchet and pawl mechanism comprises an armature38 fixedly mounted, in any suitable manner on a shaft 39. This shaft is,in turn, pivotally mounted on legs 40' extending from an extension 40 ofthe frame and has fixedly mounted thereon an arm-4l carrying at itsouter end a pivotally mounted pawl 42 biased into engagement with theratchet wheel 25 by a spring 43. The arm 4| is normally biased towardthe ratchet wheel 25, as shown in Figs. 1 and 3, by a coil spring 44having one end connected to the frame l2 and the other end connected toan arm 45 carried by the shaft 39. The bias of the spring 44 is adaptedto be overcome by the force exerted on the arm 45 through the shaft 39when the magnet 2| is energized. At the upper end of the arm 4i there isprovided an insulating member 45 for making and breaking contact betweenthe pair of contact springs included in the spring assembly 31. It willbe apparent from the preceding description that with this form of motormechanism, the cylinder ID is rotated on the back-stroke of the arm 4|by the spring 44, l. e., when the magnet 2| is deenergized following itsenergization. The energization of the magnet 2| only serves to conditionthe motor to step the cylinder one step in a counterclockwise, directionby rotating the shaft 39 to cause the translation of the pawl 42 fromengagement with one tooth of the ratchet wheel 25 into engagement withthe next succeeding tooth. In order to retain the cylinder [,0 in anyposition to which'it is stepped there is provided a spring 41 mounted onthe frame l2 and having a finger biased into engagement with the teethof the ratchet wheel 25.

' In assembling the parts of the switch, the parts of the motormechanism 20 are first mounted on the frame [2, and following this, theelements shown in Fig. 2 comprising the cylinder III, are mounted withinthe side frame members 29 and 30 by first inserting the leftend of theshaft ll through the opening in the frame member 30'. The ratchet wheel25 and nut 28 are then slipped on the left end of the shaft and theextreme left end of the shaft is inserted in the opening in the sidemember 29. Thereafter; the assembly of the switch is completed bymounting the frame member 30 on the main portion of the frame l2 byaccommodating mounting screws or brilts.

Referring now more specifically to Figs. 2 and 5, there is illustratedthe arrangement of the conducting segments and wipers, whereby thesegments are twice utilized during each revolution of the cylinder ill.As shown in these two figures, the conducting segments are spirallyarranged within a segment of the circumferential surface of the cylinderIII. This segment for the switch shown is of a width slightly less thanone-half of the circumference of the cylinder Ill. The conductingsegments are, in the arrangement shown, arranged in sets of threesegments each and means comprising multiple conductors 5i, 52 and 53,are provided for electrically connecting the corresponding segments ofeach 'set together.

bvlously the number of segments in each set will, in any givenapplication of the switch, depend upon the number of conductors in thelines incoming and the linesoutgoing from the switch. Thus, when used inthe type of telephone system briefly described above, employing two lineconductors and a control or test conductor, three conducting. segmentsare required in each set.

For the purpose of connecting a line incoming to i the switch to theseconducting segments, the three wipers indicated in Fig. 2 at 54, 55 and56 are provided which engage conducting strips 51, 58

and 59, respectively, extending continuously around the bottom of thethree guide grooves at the extreme left end of the cylinder in. Theseconducting strips are connected to the multiple conductors 5l, 52 and53, respectively, so that a line incoming to the switch and connected tothe wiper set 54, 55, 56 is multipled to each of the sets of conductingsegments. As illustrated in Fig. 1, each set of three wipers with theexception of the set comprising the wipers 54, and 56 is adapted to beconnected to a line outgoing from the switch. These wipers are arrangedin two groups with'the wipers of one group engaging the cylinder inalong a line diametrically opposite the line of engagement between thewipers of the other group and the cylinder so that the two lines ofengagement define a segment of the surface of the cylinder which is of.slightly greater width than that of the segment within which theconducting segments are confined. With this arrangement, and when thecylinder is stepped from position to position during operation of thestepping magnet 2| and its associated ratchet and pawl mechanism, thecommutating segments successively engage and disengage, at the rate ofone segment set for each step, the respective associated wipers of onegroup for one-half of a revolution of the cylinder l0 and, during theother half of the revolution, they successively engage and disengage, atthe same rate, the respective associated wipers in the other wipergroup. Thus, the wipers 54, 55 and 56 are successively connected to thewipers in each of the wipersets comprising the two wiper groups duringeach revolution of the cylinder. Obviously, the design of the switch maybe varied so that the number-of sets of conducting segments embodied inthe switch may within limits be adapted to the requirements of aparticular installation. This may be accomplished by increasing'ordecreasing the length of the cylinder 11] and varying the spacing of thesegments around the circumference of the cylinder. In the specificapplication described a fifty point switch is contemplated; that is, aswitch having twenty-five sets of grooves and conducting segments andtwo wiper groups of twenty-five wipers each, in addition to the commonwipers 54, 55, and 56 which are adapted to be connected to theconductors of the line incoming to the switch and to engage theconducting strips 51, 58 and 59, respectively.

Referring again to the system as shown in Fig. 1 and more particularlyto the use of the switch 1111 in the capacity of a non-homing lineswitch, a cut-off relay R140 and a line relay R150 are required forcontrolling the operation thereof. These relays are preferably mountedtogether and are of the form shown and described at page 49 of the bookby Kempster B. Miller entitled Telephone Theory and Practice, AutomaticSwitching and Auxiliary Equipment, published by McGraw HillPublishing-Company, Inc., in 1933. As disclosed in this book, amechanical interlock between the two relays is provided which performsthe functions described in detail hereinafter. As pointed out above, theoperation of this switch to find a trunk line leading to an idle firstselector switch is initiated by the subscriber at the telephone Alifting his receiver from its hook to place a direct current bridgeacross the conductors 016i and C162, comprisingthe line conductors ofthe calling subscribers line 100. When this occurs, a circuit iscompleted for energizing the slow-to-operate relay 150, this circuitextending from ground at R0146 by way of the elements HA1, Ci61, thebridge across Ci61 and C162 at the substation A, Ci62, RAIN, RCIM andthe winding of R150 to battery. In response to its energization over theabove traced circuit, R150 operates to apply, at RA152, busying groundto the test conductor C163 of the line 100 and to complete at thecontacts associated with RA151, a test circuit for testing the conditionof the trunk lines 121, 122, 123, 124, etc., outgoing from the lineswitch 110. In order to prevent a premature or false operation of R140,this relay is constructed so that the armature R-A151 operates beforeRA152 to permit testing of the outgoing trunk connected to the lineincoming to the switch i111 and operation of the switch to a positioncorresponding to a succeeding trunk before the relay R140 operates. Withthe cylinder 11] in a given position, such that one of the trunk lines,as, for example, the line 121, is connected by way of its terminatingwipers 16, 1'1 and 18,'the conducting segments in engagement with thesame,

I the multiple conductors 51, 52 and 53, and the wipers 54, 55 and 56,to the control means for the line switch 110, the condition of this lineis de termined by the potential which exists on the control conductorthereof, which conductor terminates at the wiper 16 and is connectedthrough to the wiper 56. If the distant selector switch connected to theline is busy, ground is present on this conductor, whereas if the lineis idle, the conductor is open circuited. Assuming that the lines 121,122 and 123 lead to busy selector switches, and the cylinder 15 is in aposition such that the conducting segments associated with the wipersterminating the line 121 are connected to the common wipers 54, 55 and56, when R155 opcrates a circuit is completed for energizingthe magnet21 of the line switch 115. This circuit starts from ground on the testconductor of the line 121 by way ofthe wiper 16, the segment 15, theconductor 53; the conducting strip 55, the wiper 56, C165, RA141,-RC149,RA151, C154, the winding of the magnet 21 and theinterrupting springs 31to battery. Thereupon, the magnet operates its armature 36 preparatoryto stepping the cylinder 10 one step, or to a position corresponding tothe trunk line 122. When the magnet 21 attracts its armature 36, theabove traced circuit over which it was energized is interrupted at thecontact springs in the spring assembly 2'1, thereby to cause this magnetto restore its arms.- ture and step the cylinder 15 one step. When thisoccurs, the segments in engagement with the wipers connected to the line121 become disconnected thereirom, and the segments associated with thewipers terminating the line 122 are rotated into engagement therewith.Since in the case assumed, this line 122 also leads to a busy selectorswitch ground is again applied to the common test wiper 56, so that themagnet is again energized and deenergized causing the cylinder 11] to bestepped a second step. This operation continues until the cylinder isstepped to a position such that a line leading to an idle selectorswitch is connected to the wipers 54 to 56, inclusive. In the presentassumed case, this occurs following three stepsof the cylinder, suchthat the segments associated with the wipers terminating the line 124are brought into engagement therewith. Since the selector switch 125 isidle, ground is not applied to the test wiper 56 and the magnet 21 isnot sumciently energized to attract its armature 38. It will be notedthat when the operation of the switch 1111 is initiated the winding ofR141] is maintained short circuited so long as ground is held on theconductor C165 from the control conductors of the trunks 121, 122, 123,etc. This short circuiting path extends from ground on C165 by way ofRA141, R0149, RA151, the winding of R140, C163 and back to ground atRA152. Thus, the relay R1411 is prevented from operating until an idletrunk outgoing from the switch 110 is found. Further to insure thisresult the engaging portions of the wipers 16, 1'1, 18, etc., areconstructed so that during the transfer of connections from one set ofwipers to the succeeding set, both sets are connected to the commonwiper set 54, 55, 56, thereby continuously to maintain ground on C165until a trunk leading to an idle selector switch is found.

When ground is removed from the test wiper 56, R is energized in serieswith the magnet 21 over a circuit extending from ground at RA152 by wayof C153, the winding of R140, C164, the winding of the magnet 21 and theinterrupting sprin'gs31 to battery. The magnet does not operate itsarmature 26 when energized in series with R140 and consequently, thecylinder 15 remains in a position corresponding to the line 124. Therelay R140, however, operates when energized over the above tracedcircuit and extends at its armatures RA141 and RA144, the loop to theselector switch 125, thereby to' cause the energizstion and operation ofthe line and hold relays conventionally provided in this switch. whenthe hold relay of the selector switch 125 operates it applies ground tothe common test wiper 56, thereby to provide a holding circuit for R145,this holding circuit extending from ground on C by way the winding ofthe magnet 2| and the springs 31 to battery. At RAI and RAHI and theirrespective associated contacts, RCMB and RCMZ, the relay RIM! interruptsthe original circuit over which RISO was energized causing-this relay torestore. The retention of ground on the control conductor Cl63 maintainsthe calling line I00 marked as busy in the bank contacts of theconnector switches to which this line extends. With the line switch H0in this condition, the calling line is connected through to the selectorswitch I and RIM) is locked up in its operated position. This conditionprevails until the switch train including the line switch 0 is released.During the release of the switch train, the control equipment associatedtherewith is restored to normal -by the removal of ground from thecontrol con- 'ductor of the trunk line I24, thereby to interrupt theholding circuit for RIM. When this relay restores, the line switch isentirely released, the cylinder I0 remaining in the position to which itwas operated during the selection of an idle selector switch.

On an incoming call to the line I00, ground is placed on the testconductor CISS, which completes the above traced circuit for energizingRIM! and the magnet 2! in series. Although RIM! partially operates it isprevented from completing its operation by the above noted mechanicalinterlock between this relay and the line relay R150,

this interlock being released to permit RIM] fully to operate only whenRI 550 is energized. The partial operation of Rl ill opens all circuitsat its spring contacts-removing all bridges or attachments to the lineswitch, thereby preventing connection with a selector switch.

Although the switch described above has been shown only in its use as aline switch of the nonhoming typ it will be apparent to those skilled inthe art that the structure embodied therein is susceptible of many otherapplications. Thus, by suitably arranging the control equipment and withbut slight modification of the structure shown, the switch may beadapted to function in the manner of a rotary switch of the homing type,or one in which the switch is restored to normal during the release of aconnection involving the same. a

While there has been described what is at present considered to be thepreferred embodiment of the invention, itv will be understood that manymodifications may be made in the structure thereof, and it iscontemplated in the appended claims to cover all such modifications asfall within the true spirit and scope of the invention.

that only the wipers of one of said groups successively engage theirrespective associated segments during a predetermined relative movementbetween said cylinder and wipers and only the Wipers. of the othergroupsuccessively. engage their respective associated segments duringanother predetermined relative movement between said cylinder and.wipers.

'2. Automatic switching apparatus comprising a cyliriderarranged forrotation, means for 1mparting rotary movement to said cylinder,conducting segments mounted on said cylinder, and two groups oi. wipers,each of said wipers being insulated from each of the other wipers, eachof said segments being adapted ,to engage only one wipers of each ofsaid groups during a revolution of said cylinder and said wipers beingso arranged 'relative to said segments that only the wipers of one ofsaid groups are successively engaged by their respective associatedsegments during a portion of said revolution and only the wipers oi the,other of said groups are successively engaged by their respectiveassociated segments during another portion of said revolution.

3QAutomatic switching apparatus comprising a cylinder arranged forrotation, means for imparting rotary movement to said cylinder,conducting segments mounted on said cylinder, means electricallyconnecting said segments together, means adapted to connect oneconductor of a line incoming to said switching apparatus to saidsegments, and two groups of wipers, each of. said wipers being insulatedfrom each of the other wipers and being adapted to be connected to oneconductor of a line outgoing from saidswitching apparatus, eachof saidsegments being adapted to engage only one wiper of each of said groupsduring a revolution 01' said cylinder and said wipers being soarrangedrelative to said segments that only the wipers of one of saidgroups are successively engaged by their respective associated segmentsduring a portion of said revolution and only'the wipers of the other ofsaid groups are successively engaged by their respective associatedsegments during another portion of said revolution. J

4. Automatic switching apparatus comprising a cylinder arranged forrotation, means for imparting rotary movement to said cylinder,conducting segments mounted on said cylinder, means electricallyconnecting said segments together, means adapted to connect oneconductor of a line incoming to said switching apparatus to saidsegments, said last mentioned means comprising a conducting stripencircling said cylinder .and connected to said segments and a wiper forcontinuously engaging said strip, and two groups of wipers, each of saidwipers being insulated from each of the other wipers and being adaptedto be connected to one conductor of a line outgoing from said switchingapparatus, each of said segments being adapted to'engage only one wiperof each of said groups during a revolution of said cylinder and saidwipers being so arranged relative to said segments that only the wipersof one of said groups are successively engaged by i their respectiveassociated segments during a portion of said revolution and only thewipers of the other of said groups are successively engaged by theirrespective associated segments during another portion of saidrevolution.

5. Automatic switching apparatus comprising a cylinder arranged forrotation, means for imparting rotary movement to said cylinder, saidcylinder having guide grooves therein. a conducting segment mounted onsaid cylinder in each of said grooves,'means electrically connectingsaid segments together, means adapted to connect one conductor of a lineincoming to said switching apparatus to said segments, and two groups ofwipers, each or said wipers being insulated from each of the otherwipers and being adapted to be connected to a line outgoing from saidswitching apparatus, each of said wipers including a portion riding inone of said grooves for engaging the conducting segment therein, each ofsaid segments being adapted to engage only one by their respectiveassociated segments duringa portion of said revolution and only thewipers o! the other of said groups are successively engaged by theirrespective associated segments during another portion of saidrevolution.

6. Automatic switching apparatus comprising a frame, a cylinderrotatably mounted on said frame, means mounted on said frame forimparting rotary movement to said cylinder, conducting segments mountedon said cylinder, means electrically connecting said segments together,means adapted to connect one conductor of a line incoming to saidswitching apparatus to said segments, an insulating member mounted onsaid frame, and two groups of wipers supported by said insulatingmember, each of said wipers being adapted to be connected to oneconductor of a line outgoing from said switching apparatus, each of saidsegments being adapted to engage only one wiper of each of said groupsduring a revolution of said cylinder and said wipers being so arrangedrelative to said segments that during a portion of said revolution onlythe wipers of one of said groups are successively engaged by theirrespective associated segments and during another portion of saidrevolution only the wipers of the other of said groups are successivelyengaged by their respective associated segments.

7. Automatic switching apparatus comprising a frame, a cylinderrotatably mounted on said frame, means mounted on said frame for impart?ing rotary movement to said cylinder, said cylin der having guidegrooves therein, a conducting segment mounted on said cylinder in eachof said grooves, means electrically connecting said seg ments together,means adapted to connect one conductor of a line incoming to saidswitching apparatus to said segments, an insulating member mounted onsaid frame, and two groups of wipers supported by said insulatingmember, each of said wipers being adapted to be connected to oneconductor of a line outgoing from said switching apparatus and includinga portion riding in one 01' said grooves for engaging the conductingsegment therein, and said segments being so arranged relative to saidwipers that each of said segments engages only one wiper of each of saidgroups during a revolution of said cylinder, only the wipers of one ofsaid groups are successively engaged by their respective associatedsegments during a portion of said revolution and only the wipers of theother of said groups are successively engaged by their respectiveassociated segments during another portion of said revolution.

8. Automatic switching apparatus comprising a frame, a cylinderrotatably mounted on said frame, means mounted on said frame forimparting rotary movement to said cylinder, said cylin der having guidegrooves therein, a conducting segment mounted on said cylinder in eachof said grooves, means electrically connecting said segments together,means adapted to connect one conductor of a line incoming to saidswitching apparatus to said segments, an insulating member mounted onsaid frame, and two groups of wipers supported by said insulatingmember, each of said wipers being adapted to be connected to one ammo-rconductor of a line outgoing from said switching apparatus and includinga portion riding in one of said grooves tor engaging the conductingsegment therein, each of said segments being provided with a V-shapedslot therein the sides of which are adapted to make a two point contactwith the associated wipers, and said segments being so arrangedrelativeto said wipers that each of said s ments engages only one wiperor each of said groups during a revolution of said cylinder, only thewipers of one 0! said groups are successively engaged by theirrespective associated segments during a portion of said revolution andonly the wipers of the other of said groups are successively engaged bytheir respective associated segments during another portion oi saidrevolution.

9. Automatic switching apparatus comprising a cylinder arranged forrotation, means for imparting rotary movement to said cylinder,conducting segments mounted on said cylinder, said segments beingconfined within a segment of the circumferential surface of saidcylinder, and two groups of wipers, each of said wipers being insulatedfrom each of the other wipers, each of said conducting segments beingadapted to engage a wiper of each of said groups during a revolution ofsaid cylinder, and the wipers of said two groups being disposed toengage said cylinder along two different lines which define a segment ofthe surface of said cylinder of slightly greater width than that of thesegment within which the conducting segments are confined, whereby thewipers of one of said groups are successively engaged by theirrespective associated conducting segments during a portion of arevolution of said cylinder and the wipers of the other of said groupsare successively engaged by their respective associated conductingsegments during another portion of said revolution.

10. Automatic switching apparatus comprising a cylinder arranged forrotation, means for imparting rotary movement to said cylinder,conducting segments mounted on said cylinder, said segments beingspirally arranged within a segment of the circumierential surface ofsaid cylinder, and two groups of wipers, each of said wipers beinginsulated from each of the other wipers, each of said conductingsegments being adapted to engage a wiper of each of said groups during arevolution of said cylinder, and the wipers of said two groups beingdisposed to engage said cylinderalong two different lines which define asegment of the surface of said cylinder of slightly greater width thanthat of the segment within which the conducting segments are confined,whereby the wipers oi one of said groups are successively engaged bytheir respective associated conducting segments during a portion of arevolution of said cylinder and the wipers of the other of said groupsare successively engaged by their respective associated conductingsegments during another portion of said revolution.

11. Automatic switching apparatus comprising a cylinder arranged forrotation, means for imparting rotary movement to said cylinder,conducting segments mounted on said cylinder, said segments beingspirally arranged within a segment comprising slightly less thanone-half the circumferential surface of said cylinder, and two groups ofwipers, each of said wipers being insulated from each of the otherwipers, each of said conducting segments being adapted to engage a wiperof each of said groups during a revolution of said' cylinder, and thewipers oi said two groups being disposed to engage said cylinder alongtwo diametrically opposite line s, whereby the wipers of one of saidgroups are successively engaged by their respective associatedconducting segments during one-half of said revolution, and the wipersoi the other of said groups are successively engaged by their respectiveassociated conducting segments during the other half of said revolution.

12. Automatic switching apparatus comprising a cylinder arranged forrotation, means for imparting rotary movement to said cylinder,conducting segments mounted on said cylinder, means electricallyconnecting said segments together, means adapted to connect saidsegments to one conductor of a line incoming to said switchingvapparatus, said segments being spirally arranged within a segmentcomprising slightly less than one-half the circumferential surface ofsaid cylinder, and two groups of wipers, each of said wipers beinginsulated from each of the other wipers and being adapted to beconnected to one conductor of a line outgoing from said switchingapparatus, each of said conducting segments'being adapted to engage awiper of each of said groups during a revolution of said cylinder, andthe wipers of said two groups being disposed to engage said cylinderalong two diametrically opposite lines, whereby the wipers clone of saidgroups are successively engaged by their respective associatedconducting segments during onehalf of said revolution and the wipers ofthe other of said groups are successively engaged by their respectiveassociated conducting segments during,

the other half or said revolution.

13. Automatic switching apparatus comprising a frame, a cylinderrotatably mounted on said frame, means mounted on said frame forimparting rotary movement to said cylinder, said cylinder having guidegrooves therein, a conduct-- ing segment mounted on said cylinder ineach of said grooves, means electrically connecting said segmentstogether, means adapted to connect said segments to one conductor of aline incoming to said switching apparatus, said segments being spirallyarranged within a segment comprising slightly less than one-half thecircumferential surface of said cylinder, and two groups of wiperssupported on said frame, each of said wipers being insulated from eachof the other wipers and being adapted to be connected to a line outgoingfrom said switching apparatus, each of said wipers including a portionriding in one of said grooves for engaging the conducting segmenttherein, each of said segments being adapted to engage a wiper of eachof said groups during a ,revolution of said cylinder and the wipers ofsaid means mounted on said frame for imparting stepby-step' rotarymovement to said'cylinder, said cylinder having guide grooves therein, aconducting segment mounted on said cylinder in each of said grooves,means electrically connecting said segments together, means adapted toconnect said segments to one conductor of a line incoming to saidswitching apparatus, said conducting segments being spirally arrangedwithin a segment comprising slightly less than one-half thecircumferential surface of said cylinder, an insulating member mountedon said frame, and two groups of wipers supported by said insulatingmember, each of said wipers being insulated from each of the otherwipers and being adapted to be connected to one conductor oi a lineoutgoing from said switching apparatus, each of said wipers including aportion riding in one of said grooves for engaging the conductingsegment therein, each of said conducting segments being adapted toengage a wiper of-each of said groups during a revolution of saidcylinder, and the win ers of said two groups being disposed to engagesaid cylinder along two diametrically opposite lines, whereby the wipersof one of said groups are successively engaged by their respectiveassociated conducting segments during one-half oi said revolution andthe wipers of the other of said group's are successively engaged bytheir respective associated conducting segments during the other half ofsaid revolution.

4 JOHN E. OSTLINE.

